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Close but no cigars

14 Jan 2020 08:40
Pillsbury
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Close but no cigars #1
In the off season I play with the race bike to try to improve things. One thing I have been trying to do is to get a straight cut gear set for this old DT1 motor. In 2 years I have not been able to locate a set.
I do a lot of research on what I can find, sometimes it works, this time it did not (yet?)
I picked up an '89 YZ250 clutch pack & engine pinion gear. The clutch fits perfect, it is a bolt in replacement, bearing thrust washers everything!:likey

The problem is..........the spacing between the gears is farther, so the stock pinion gear is 1 tooth to small to mesh correct. It uses a 22 tooth (fits motor spline perfect) But needs a 23 tooth to fit, which would increase the primary drive ratio. Not a bad thing on a road racer but would suck on a dirt bike. From what I have searched, there is no 23T pinion gear available from Yamaha.

So, back to searching for a DT1 (MX) set:Ugh

1970 DT1-C Grand Prix race bike
1970 DT1-C Street tracker
1968 Honda CL90
1973 Honda CR250
1974 Honda MR-50
1966 Triumph Tiger Cub
1970 Suzuki TC90
1947 Mustang
1974 Suzuki TC185
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15 Jan 2020 13:59
FrankC
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Close but no cigars #2
The junk men of old at the salvage yards probably could have helped back when,but alas that knowledge has disappeared unfortunately. Probably be bucks to have a gear made unless you know somebody. It is good to know you found a clutch basket that works if the ring gear is swapped out. That is an awesome find brother.

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15 Jan 2020 14:46
Enduronut
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Close but no cigars #3
.

My son and I have discussed making a limited production run of both the smaller AT/CT set, and the DT/RT set, but the soonest we would move on that, is a couple years up the road ... when he retires from the US Air Force.

Wish I could help, but the ones I have will be needed as prototypes. If we do move on this idea, we'll probably only make a dozen sets of each, because it's a fairly substantial investment.

.

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15 Jan 2020 16:05
Pillsbury
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Close but no cigars #4

Enduronut wrote: .

My son and I have discussed making a limited production run of both the smaller AT/CT set, and the DT/RT set, but the soonest we would move on that, is a couple years up the road ... when he retires from the US Air Force.

Wish I could help, but the ones I have will be needed as prototypes. If we do move on this idea, we'll probably only make a dozen sets of each, because it's a fairly substantial investment.

.


Good to hear, put an add in the AHRMA monthly mag and you might sell quite a few.

1970 DT1-C Grand Prix race bike
1970 DT1-C Street tracker
1968 Honda CL90
1973 Honda CR250
1974 Honda MR-50
1966 Triumph Tiger Cub
1970 Suzuki TC90
1947 Mustang
1974 Suzuki TC185

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15 Jan 2020 16:09
Pillsbury
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Close but no cigars #5

FrankC wrote: The junk men of old at the salvage yards probably could have helped back when,but alas that knowledge has disappeared unfortunately. Probably be bucks to have a gear made unless you know somebody. It is good to know you found a clutch basket that works if the ring gear is swapped out. That is an awesome find brother.


Yes, much more area on this clutch & stronger springs, should not slip. I'm still looking as it seems Yamaha used the same motor spline even on the 500. This fits too good not to happen!!! :huh:

1970 DT1-C Grand Prix race bike
1970 DT1-C Street tracker
1968 Honda CL90
1973 Honda CR250
1974 Honda MR-50
1966 Triumph Tiger Cub
1970 Suzuki TC90
1947 Mustang
1974 Suzuki TC185
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